Based on the field survey and analysis of representative traditional time-honored shops in Xi'an City,specific measures for protecting their space environment were put forward,and the sustainable preservation and ...Based on the field survey and analysis of representative traditional time-honored shops in Xi'an City,specific measures for protecting their space environment were put forward,and the sustainable preservation and development pattern of such intangible cultural heritages in the future urban development was established.展开更多
In digital substations with power transformers, the key to implementation of line differential protection is synchronization of electrical quantities at both two sides. System framework of current differential protect...In digital substations with power transformers, the key to implementation of line differential protection is synchronization of electrical quantities at both two sides. System framework of current differential protection for lines between digital substations is analyzed briefly, as well as the necessity of demand for time synchronization. Principle of time synchronization based on GPS and IEEE1588 PTP (Precision Time Protocol) are introduced. Time synchronization of current differential protection between digital substations based on IEC61850 is discussed. This paper puts forward two solution schemes of time synchronization, analyzes their advantages and disadvantages respectively, and points out that the development direction of time synchronization of differential protection between digital substations is IEEE1588 PTP.展开更多
The intelligent substation realizes the digitization of information in the whole substation and thus time synchronization system becomes more and more important. This paper introduces time synchronization technology o...The intelligent substation realizes the digitization of information in the whole substation and thus time synchronization system becomes more and more important. This paper introduces time synchronization technology of intelligent substation and puts forward the principles for designing intelligent substation time synchronization system. According to some relay protection malfunction examples caused by time synchronization system fault, analyze the influence of time synchronization system fault to relay protection and correspondingly put forward some improving measures.展开更多
This study compares numerical models with analytical solutions in computing travel times and radius of protection zones for a pumping well located in an unconfined aquifer with uniform recharge and in a semi-confined ...This study compares numerical models with analytical solutions in computing travel times and radius of protection zones for a pumping well located in an unconfined aquifer with uniform recharge and in a semi-confined aquifer. Numerical models were capable of delineating protection zones using particle tracking method in both cases. However, protection zones defined by travel time criterion can only protect small percent of source water to the well; large percent of source water is not protected which may pose a risk of pollution of source water to the well. The case study of Leggeloo well field in the Netherlands indicates that although a well field protection area was enforced in 1980 s, elevated nitrate concentration has been monitored in the abstracted water since 1990 s. The analysis of protection areas shows that the current protection area only protects 37.4% of recharge water to the well field. A large protection area must be adopted in order to safeguard the sustainable water supply for the local community.展开更多
Game model of environmental protection at scenic spots is established in this paper in order to carry out analysis of the equilibrium between one-time game and infinitely repeated game, disclose the reasons why the en...Game model of environmental protection at scenic spots is established in this paper in order to carry out analysis of the equilibrium between one-time game and infinitely repeated game, disclose the reasons why the environment of scenic spots are destroyed, and propose the countermeasures to ensure the equilibrium of the game. The study also reveals that during the one-time game between tourists and tour operators, it is tour operators' dominant strategy not to control environmental pollution that leads to the destruction of environment at scenic spots. While, during the infinitely repeated game between tourists and tour operators, the realization of Pareto optimality equilibrium (The strategy of tourist is traveling, and the strategy of tour operators are controlling environmental pollution) is dependent upon the choice of players (tourists or operators) of triggering strategy (traveling or controlling environmental pollution). The supervision of the government upon operators can force them to control environmental pollution, which can consequently improve the efficiency of equilibrium in the game, and promote environmental protection at tourism scenic spots and sustainable development of tourism.展开更多
文摘Based on the field survey and analysis of representative traditional time-honored shops in Xi'an City,specific measures for protecting their space environment were put forward,and the sustainable preservation and development pattern of such intangible cultural heritages in the future urban development was established.
文摘In digital substations with power transformers, the key to implementation of line differential protection is synchronization of electrical quantities at both two sides. System framework of current differential protection for lines between digital substations is analyzed briefly, as well as the necessity of demand for time synchronization. Principle of time synchronization based on GPS and IEEE1588 PTP (Precision Time Protocol) are introduced. Time synchronization of current differential protection between digital substations based on IEC61850 is discussed. This paper puts forward two solution schemes of time synchronization, analyzes their advantages and disadvantages respectively, and points out that the development direction of time synchronization of differential protection between digital substations is IEEE1588 PTP.
文摘The intelligent substation realizes the digitization of information in the whole substation and thus time synchronization system becomes more and more important. This paper introduces time synchronization technology of intelligent substation and puts forward the principles for designing intelligent substation time synchronization system. According to some relay protection malfunction examples caused by time synchronization system fault, analyze the influence of time synchronization system fault to relay protection and correspondingly put forward some improving measures.
文摘This study compares numerical models with analytical solutions in computing travel times and radius of protection zones for a pumping well located in an unconfined aquifer with uniform recharge and in a semi-confined aquifer. Numerical models were capable of delineating protection zones using particle tracking method in both cases. However, protection zones defined by travel time criterion can only protect small percent of source water to the well; large percent of source water is not protected which may pose a risk of pollution of source water to the well. The case study of Leggeloo well field in the Netherlands indicates that although a well field protection area was enforced in 1980 s, elevated nitrate concentration has been monitored in the abstracted water since 1990 s. The analysis of protection areas shows that the current protection area only protects 37.4% of recharge water to the well field. A large protection area must be adopted in order to safeguard the sustainable water supply for the local community.
基金Supported by Scientific Research Initiation (Supporting) Funds of Northwest A&F University~~
文摘Game model of environmental protection at scenic spots is established in this paper in order to carry out analysis of the equilibrium between one-time game and infinitely repeated game, disclose the reasons why the environment of scenic spots are destroyed, and propose the countermeasures to ensure the equilibrium of the game. The study also reveals that during the one-time game between tourists and tour operators, it is tour operators' dominant strategy not to control environmental pollution that leads to the destruction of environment at scenic spots. While, during the infinitely repeated game between tourists and tour operators, the realization of Pareto optimality equilibrium (The strategy of tourist is traveling, and the strategy of tour operators are controlling environmental pollution) is dependent upon the choice of players (tourists or operators) of triggering strategy (traveling or controlling environmental pollution). The supervision of the government upon operators can force them to control environmental pollution, which can consequently improve the efficiency of equilibrium in the game, and promote environmental protection at tourism scenic spots and sustainable development of tourism.
